Apparatus for plastic lining containers for aerosols

ABSTRACT

A fluid containing a polymerizable film forming substance is introduced into a container so as to adhere to the inner walls thereof. The nonadhering portion of the liquid is then withdrawn and the remainder polymerized in situ on the inner surface of the container. Alternatively, the container is a mold coated with a parting compound and the film formed therein is separated from said mold after polymerization.

United States Patent [7 21 Inventors Charles Paoletti Aulnay-sous-Bois; Gilles Terrasse, Deuil-la-Barre, both of France [211 App]. No. 843,617

{22] Filed July 22, 1969 [45] Patented Oct. 12,1971

[73 Assignee Societe anonyme dite: L'Oreal Paris, France [32} Priority Aug. 13, 1968 [33] France 1 1 162,937

[54] APPARATUS FOR PLASTIC LlNlNG CONTAINERS FOR AEROSOLS 5 Claims, 1 Drawing Fig.

[52] U.S. C1 118/408, 18/5 BM, 18/3()GM,141/47,141/59 [51] Int. CL; B05c 7/00 Primary Examiner.lohn P. Mclntosh Attorney-Holcombe, Wetherill & Brisebois ABSTRACT: A fluid containing a polymerilable film forming substance is introduced into a container so as to adhere to the inner walls thereof. The nonadhering portion of the liquid is then withdrawn and the remainder polymerized in situ on the inner surface of the container. Alternatively, the container is a mold coated with a parting compound and the film formed therein is separated from said mold after polymerization.

APPARATUS FOR PLASTIC LINING CONTAINERS FOR AEROSOLS SUMMARY OF THE INVENTION The objects of the present invention are to provide:

An apparatus for applying coatings or linings of plastic material to the inside of hollow containers of any shape or nature.

In particular, it envisages the protection of glass containers which are to hold products under pressure such as containers for aerosol.

If the container breaks or explodes the plastic linings make itpossible to prevent the outward projection of fragments and the accidents which may result therefrom. In order to store aqueous products it is preferred to use plastisols or organosols consisting of dispersions of very fine resinous particles in solvents or plasticizers, or in mixtures of such solvents or plasticizers, possibly in association with colored pigments.

Vinyl plastisols and organosols are particularly useful.

Depending on the nature of the coating product used, it is sometimes necessary to first apply an adhesive layer consisting, for. example, of a product having an acrylic resin base to the inner wall of the container before applying the plastic coating itself.

In order to facilitate the application of such a dispersion, or such other dispersions as polyurethane, polyesters, and catalyzed epoxy products, which are more resistant to the action of solvents essences and essential oils which do not swell, dissolve, or cause them to deteriorate, when the containers are designed to hold nonaqueous products, the container to be coated is first brought to a suitable temperature, which may for example be from 150-160 C. for a plastisol having a polyvinyl chloride base.

The container is then filled with-the said liquid product, so as to entirely cover the inner wall of the container. This is done under a certain gaseous pressure which tends to apply the dispersion to the inner wall of the container.

At the end of from 15-40 seconds, for example, depending onhow thick a dry film is desired, the excess liquid which has not adhered to the wall is withdrawn by means of a suction tube of any suitable shape.

The temperature of the container and the gel adhering to its inner wall is then increased, for example,,to from l80-200 C. for a time between 5 and 20 minutes so as to cause the polymerization of the internal coating, which then takes the fonn of a continuous flexible film of constant thickness.

Depending on whether a primary adhesive layer has been applied, or on the contrary an antiadhesive layer, and particularly a coating of the phenolic epoxy type containing a parting compound such, for example, as the one sold in the United States under the trademark ACRAWAX by the Glyco Chemical Co. and sold in France by the Organon Company, the coating will adhere or fail to adhere to the internal wall of the container or of the heating mold.

The process according to the invention may also be carried out by using powdered polyolefines, polyamides, epoxy resins, or polyvinyl chloride powders.

These powders are first modified by adding antistatic compounds, dyes, stabilizers, and possibly pigments. The grade and granulometry of these powders are, in the case of a polyolefine, between 40 and 70 and between 100 and 300 microns respectively.

The homogeneous mixture prepared in this manner is injected into a container which has first been heated to a temperature of the order of 200250 C. This injection may be made by using a screw or a piston.

When the container is full of powder to the height to which it is to be coated, the system is hermetically sealed and the powder therein placed under a pressure of about 2 kg./cm. for several seconds. The excess powder which does not adhere to the inner wall of the container is then removed, possibly after a certain lapse of time, by means of a vacuum pump or any other adequate apparatus.

The container and the mixture adhering to its inner wall are then heated to a temperature of the order of 230 C., for example, for several minutes, so as to fuse the coating until a continuous film is obtained, This coating is flexible and of constant thickness and is more or less adherent to the wall of the container.

Suitable apparatus for injecting the powders comprises a piston actuated by an electromagnet, which piston operates in a cylinder which terminates in a smaller cylinder which may be brought into contact with a preheated container and into which the powder is to be injected.

In order to avoid having this powder stick to the piston, the piston is preferably water cooled.

The apparatus also comprises funnel shaped centering means which terminates in a tube within which said screw is located, said screw being driven in rotation by a motor.

The characteristics of the present invention will be better understood from the following two examples of how the invention may be carried out, which are given purely by way of example, and from a reading of the following description of a powder-injecting device for carrying out the aforesaid process. This apparatus is likewise described purely by way of illustration and with reference to the accompanying drawings, the sole FIGURE of which discloses the said apparatus partly in elevation and partly in section.

EXAMPLE l A colorless liquid product is used which has the following composition:

pplyvinyl chloride having a molecular weight between 80,000 and 140,000 44.5 percent by weight diethyl-Z-hexylphthalate 30 percent by weight didecyl adipate 44.5 percent by weight octyl epoxy stearate (manufactured by the Argus Co. in the United States and sold in France by the Sogefra Division of the S.C.E. Co.) 10 percent by weight tri-(Z-chIoro-ethyl) phosphate 7.8 percent by weight Stabilizer having a barium, cadmium and zinc base (sold under the trademark Mark K C B by the Sogefra Division of the S.C.E. Co.) 1.3 percent optical azuring product 0.3 percent fluidizer sold under the trademark Deshydrol by the German l-lenkel Co. 1.1 percent Such a product loses at most 0.5 percent by weight of water during the above coating process.

The density of the coating obtained falls between 1.15 and 1.20.

At the moment of its injection the liquid has a viscosity at a temperature of 20 C. which falls between 1,500 and 2,500 centipoises.

The container is preheated to a temperature between and C.

The plastisol is injected through a tube up to the desired level under a gaseous pressure between 7 and 8 kg./cm.

The plastisol is left in contact with the container for 20 to 30 seconds.

The excess plastisol is eliminated by means of a vacuum pump.

The container with its internal coating is then placed in an oven at a temperature between and C. for from 10 to 15 minutes.

The result is a coating having a thickness between 0.5 and l millimeter.

EXAMPLE 2 The procedure is exactly the same as in example 1 except that a colored liquid product having the following proportions is used:

polyvinyl chloride 45.5 percent by weight various plastifiers of the four types mentioned in example 1 49.1 percent stabilizer of the type given in example 1 1.2 percent fiuidizer of the type given in example 1 1.1 percent pigments 2.7 percent EXAMPLE 3 A powdered product having the following composition is 0.3 percent 4,4'-thio-bis-( 3-methyl-6-tertiobutyl phenol) (as a heat sta bilizer) 0.7 percent lt should be noted that, instead of the above nitrate, it is possible to use a synthetic wax such as the one sold under the trademark ARTlClRE in France by the Lamotte and Coiffard Co., as an antistatic agent.

It should be noted that no useful purpose is served by using higher percentages of the antistatic agent or thermal stabilizer.

The container itself is preheated to a temperature between 200-230 C. The pulverulent mixture is then injected by means of a screw or piston, while providing means for air to escape from the container.

When the container is full the system is hermetically closed and the screw is again actuated to produce a pressure of the order of 2 kg./cm. in the container.

The powder is left in contact with the container for several seconds, for example 2-3 seconds. Then the excess mixture is eliminated by means of a vacuum pump or other suitable device.

The container, with its coating, is then placed in an oven at a temperature between 210-230 C. for -7 minutes. The resulting lining has a thickness of 0.8- l .2 millimeters.

The loss of water during cooling should not exceed 0.5 percent; the apparent density of the powder used is 0.34; and the density of the film obtained is 0.92. The granulometry of the product used is between 100 and 300 microns, with a grade between 40 and 70.

The melting point of the powder and the film obtained is 109 C. The foregoing compositions may naturally be modified depending on the opacity, the flexibility, and the mechanical strength required.

EXAMPLE 4 0.1 percent 0.3 percent heat stabilizer of one of the two types specified 0.7 percent pigments 2.6 percent Of course, the quantity of pigments depends upon the color desired and may require the percentages of the other constituents to be slightly modified.

The process which has just been described may be applied to any type of container or can, made of glass, metal, or any other material. Moreover, as has been indicated above, it is possible, by providing an antiadhesive undercoating consisting of a glaze of the phenolic epoxy type containing a parting compound, such, for example, as ACRAWAX sold by the Glyco Chemical Co., in the United States and by the Organon Co. in France to utilize as containers heated molds from which the film may be removed.

It will be readily understood that in this case it is unnecessary to place the container in an oven. 1f the mold is electrically heated, for example, it suffices to increase the intensity of the heating current so as to bring the heating mold to the required temperature, for example C., for from l0l5 minutes in the case of a plastisol having a polyvinyl chloride base or 210230 C. for 5 to 7 minutes in the case of a polyolefine coating.

Turning now to the apparatus used in carrying out the invention, the single FIGURE in the drawing shows a container 1 which is heated to the desired temperature. A cylinder 2, the lower part of which is provided with vents 3, makes it possible when the piston 4 is raised, that is to say when the electromagnet 5 is not supplied by the AC source 6, and the piston 4 is held up by the spring 7, to force out the air in the container 1, as the powder is introduced through the tube 8 containing an Archimedes screw 9, which serves to advance the powder contained in the funnel 10. A motor 1! drives a rod 12 fixed to the Archimedes screw 9, and the assembly comprising the funnel l0 and a tube 8 is centered by centering means 13 comprising screws 14.

When the container is completely filled with powder and the air has been permitted to escape through the vents 3, the electromagnet 5 is actuated in such a way as to force the piston toward the bottom of the cylinder 2, thus closing the vents 3, the container 1 being also forced against sealing means 15 carried by cylinder 20 of smaller diameter, located at the bottom of the cylinder 2.

When the piston 4 is in its lower position a pressure of the order of 2 kg. is applied to the powder by turning the screw 9 by means of a motor 11.

It will be appreciated that the embodiment of the injection means which has just been described may be modified or improved and that certain elements thereof may be replaced by their mechanical equivalents without thereby departing from the basic principles of the invention.

In particular, it is possible, when manufacturing hollow containers consisting solely of a plastic film, to prolong the duration of the injection of the liquid or powdered plastic so as to obtain a plastic film more than 1 millimeter thick.

Moreover, in this case, it is possible to use heating molds comprising several intercommunicating cells which are isolated one from the other, so as to produce at a single operation either several plastic containers or a multicellular container having plastic walls.

What is claimed is:

1. Apparatus for coating the inner wall ofa container, which apparatus comprises:

a hollow casing,

a tube extending through said casing, with the free end of the tube projecting beyond one end of said casing,

a screw for feeding material through said tube, said Screw being rotatably mounted in said tube and having an exter' nal diameter substantially equal to the internal diameter of said tube,

a piston in said casing encircling said tube, said piston making sealing contact with both said casing and said tube,

means for moving said piston between first and second positions longitudinally of said tube,

annular means at the end of said casing from which said tube projects for sealingly engaging the outside of a container into which the projecting end of said tube is inserted,

vent means in the wall of said casing through which air can escape from a container when said annular means is in sealing engagement therewith and said piston is in its first position, said vent means being located to be blocked by means biasing said piston toward its first position and electrically operable means for moving said piston from its first to its second position.

5. Apparatus as claimed in claim 1 comprising centering means carried by said casing and carrying said tube so that its position may be adjusted transversely within said casing. 

1. Apparatus for coating the inner wall of a container, which apparatus comprises: a hollow casing, a tube extending through said casing, with the free end of the tube projecting beyond one end of said casing, a screw for feeding material through said tube, said screw being rotatably mounted in said tube and having an external diameter substantially equal to the internal diameter Of said tube, a piston in said casing encircling said tube, said piston making sealing contact with both said casing and said tube, means for moving said piston between first and second positions longitudinally of said tube, annular means at the end of said casing from which said tube projects for sealingly engaging the outside of a container into which the projecting end of said tube is inserted, vent means in the wall of said casing through which air can escape from a container when said annular means is in sealing engagement therewith and said piston is in its first position, said vent means being located to be blocked by said piston from communication with said container when said piston is in its second position.
 2. Apparatus as claimed in claim 1 comprising a funnel having its smaller end connected to the end of said tube remote from said annular means.
 3. Apparatus as claimed in claim 1 comprising a motor for rotating said screw.
 4. Apparatus as claimed in claim 1 comprising resilient means biasing said piston toward its first position and electrically operable means for moving said piston from its first to its second position.
 5. Apparatus as claimed in claim 1 comprising centering means carried by said casing and carrying said tube so that its position may be adjusted transversely within said casing. 